330 



Part III. — Twenty-fourth Annual Report 



On ^5 tli December, 1901, a collection of 87 herrings was obtained at 

 Burghead Bay, in from 7^ to 18 fathoms. Two series were present, the 

 first consisting of 19 fish, ranging from 139mm. to 183mm. (5| to 7 T 3 W 

 inches) the mean being. 161mm., and the average 162'4mm., or 6-| 

 inches. These arc apparently autumn herrings over three years of age. 



The second series consisted of 68 fish, ranging from 186mm. to 

 223mm. (7y\ to 8-J inches); the modal size was about 198mm., the 

 mean 204-5mm., and the average 201mm., or 7 T f inches. These also 

 were autumn herrings over four years of age. 



The numbers are not large, but comparison of the sizes of the two 

 groups shows an increment in the year of 39'6mm,, or a little over J J 

 inches. 



On 1st April, 1904, off Findhorn, in the same neighbourhood, 497 

 herrings were obtained, the depth of the water in this case being from 

 30 to 32 fathoms. They were the largest herrings got in any of the 

 collections by means of the otter-trawl. (Plate XVIII.) 



Eleven of them belonged to one series, and ranged from 123mm. to 

 169mm., the mean size being 143mm., and the average computed 

 150'8mm., or about 5 T f inches. 



The next group consisted of 478 herrings, ranging from 177mm. to 

 228mm. (7 to 9 inches), but the series might stop about 223mm. The 

 modal size was about 200mm., the mean was 202 , 5mm , and the com- 

 puted average was 203*2mm. These herringe were therefore about 

 8 inches long, and they were spring herrings, as their position in the 

 synthetic table shows, a little over four years of age. 



Another collection from the Moray Firth was obtained in the 

 Cromarty Firth on 1st June 1901, and of the 70 taken, 66 measured 

 from 111mm. to 155mm. (4| to 6 J inches) ; the mode was 135mm. (5 T \ 

 inches), the mean was 133mm , and the computed average 129 , 7mm. or 

 5 J inches. 



These were autumn herrings approaching their third year of age. 



The next largest herrings measured by me consisted of a " cran " of 

 spring herrings, caught by drift-net, in the ordinary way, on 16th 

 February 1H04, in the neighbourhood of the Isle of May, at the mouth 

 of the Firth of Forth, and landed at Anstruther. They were actually 

 spawning, and it was thus a simple matter to separate the sexes and 

 measure them apart, a task in which Mr. William Keir, the Fishery 

 Officer of the district, was good enough to assist me. The measurements 

 will be found in Table III., and the curves on Plate XIX. 



A glance at the peculiar curve? is enough to show that the herrings 

 do not form a homogeneous group. The range is too great for one 

 series, viz., over 70mm. (2| inches) ; the oblique line on the synthetic chart 

 connecting the extreme limits of the spring herrings of various ages, 

 when prolonged, goes through the middle of the collective measure- 

 ments; and consideration of the millimetre table and the curves shows 

 that two groups are present. The males and females were measured 

 separately in two lots each, or four in all, and when curves are made 

 of these separate measurements, they all agree in having two cusps, or 

 mo les, with a depression at about 25cm. The following Table shows 

 the grouping in each of the four measurements, in *5cm., and also the 

 arrangement of the 2mm. grouping at the critical place: — 



[Table. 



